An organic light-emitting device, such as an organic electroluminescent device (organic EL device), has been actively studied for enhancing the light emission efficiency thereof. In particular, various studies for enhancing the light emission efficiency have been made by newly developing and combining an electron transporting material, a hole transporting material, a light-emitting material and the like constituting an organic electroluminescent device. Among the studies, for developing a light-emitting material having a highs light emission efficiency, extensive studies have been made from various standpoints.
In recent years, among fluorescent materials, particularly, a delayed fluorescent material emitting delayed fluorescent light is receiving attention. Delayed fluorescent light is fluorescent light that is emitted by utilizing the inverse intersystem crossing from the excited triplet state to the excited singlet state, and is observed as fluorescent light that has a longer lifetime than normal fluorescent light. By producing an organic electroluminescent device using the delayed fluorescent material, a light emission efficiency that exceeds the theoretical limit in the use of a normal fluorescent material can be achieved. Accordingly, delayed fluorescent materials having various structures have been developed. (see, for example, PTL 1).